#include <bits/stdc++.h>

using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b

using namespace std;

int main(){
    cout << fixed << setprecision(15);
    
    ll a,b,n;
    cin >> a >> b >> n;
    if (n == 0){
        print(a);
        return 0;
    }else if (n == 1){
        print(b);
        return 0;
    }
    //f0 f1 f0*f1 f0 f1 f0*f1
    if (n%3 == 0) {print(a);}
    else if(n%3 == 1) {print(b);}
    else print(ll(a ^ b));
    
    //system("pause");
    return 0;
}